Airplane heating system



Filed Feb. 14, 1941 H g/ n50 5. 114442-051 0 ATTORNEY end of the heaterstructure.

Patented not. 13, 1945;

UNITED wes PATENT OFFICE AIRPLANE ammo SYSTEM Frederic o. Hess,Germantowmand Richard E. n.

Wakefield, Aidan, Pa., assignors to Sales Corporation of America, acorporation of Pennsybvanla Application February 14, 1941, Serial No.378,916

Claims. (on. 158-28) This invention relates to heaters adapted to beoperated on liquid fuel, such as gasoline, for example, and it is anobject to provide an improvement for operating such heaters whereby .the

larity in the claims annexed to and forming a part of thisspecification. For a better understanding of the invention, however/itsadvantages and specific objects attained with its, use, reference shouldbe had to the following descriptive matter and accompanying drawing inwhich the single figure more or less diagrammatically illustrates aheater embodying the invention.

A fluid heater A embodying the invention comprises structure providingan annular heating space E having distributed heatinggas outlets B atits upper end and having its lower end closed by a burner wall 0 formedwith burner orifices C leading to the heating space B from a burnerinlet chamber D which extends across the lower The burner C isadvantageously of the type disclosed and claimed in the Hess Patent No.2,228,114, granted January '7,

- 1941, in that the burner wall is formed by radially extending laminaor plates of ceramic material with grooves in their sides, which formthe orifices C. 1

Air is 'drawn into the inlet chamber D. by a fan or blower F centrallydisposed with respect to that chamber, and a supply conduit E which maylead from the atmosphere external to the airplane in which the heater Ais mounted, opening to the chamber D at its center. is driven by anelectric motor G located within the space b surrounded by the structureforming heating space B. The motor G is cooled and some of the heatgenerated in the heating space E isgiven up to air moved through thespace b by a fan 9 driven by the motor G.

In the preferred construction shown, the blower F also serves as a meansfor mechanically atomizing a liquid fuel, such as gasoline, for example,and mixing it with the air drawn into the chamber D to form a.combustible mixture which passes through the burner orifices C into andis burned in the heating space B. The liq- Pipe H of a pump I, saidhaving its dis: charge end axially disposed relative to the blower F andextending into the space about which the inner ends of the blower Fbladesor vanes F turn. The pump I comprises an impeller rotated by anelectric motor 1A., The discharge end of the pipe H is closed except forone or more fine orifices H, each discharging a jet of liquid fuelradially into the space through which the blades'F' move. The formationof a combustible mixture of air andliquid fuel in the manner and by themeans described is the joint invention of John W. Townsend and FredericO. Hess, one of the joint applicants herein, and described and claimedin Patent No. 2,314,089, granted March 16, 1943.

The heating chamber outlets B extend radi-' ally inward from the upperportion of the heat of an exhaust fan K. The impeller of the fan K isrotated by an electric motor KA, and the products of-combustion drawnfrom the heating space B are discharged by the fan K through a dischargepipe K into the external atmosphere. A butterfly valve or damper K inthe exhaust K is connected to a regulator K shown as a bellowsdeviceadapted to expand and contract and to thereby throttle the passageK more or less as the pressure of the atmosphere is increased anddecreased by airplane altitude changes, so that combustion air andliquid fuel may be supplied to the heater at suitable rates by operatingthe blower F, fan K and pump I at proper and readily maintained speeds.

.The blower F uid-fuel thus atomized is supplied by the outlet medium inliquid form through a pipe L from the outlet of a circulating pump M.The liquid heated in the tubular coil L passes from the latter in liquidform through an outlet pipe L connected to the heat inlets 0' ofradiator elements 0. The elements 0 have their individual outlets 0connected to a return conduit 0 through which liquid discharged from theradiators is returned to the inlet of the pump M. The return conduit 0includes a heat exchanger section 0 adapted to absorb heat from thespent heating gases passing to the atmosphere through the pipe K Thereturn conduit 0 includes a section 0 which is adapted to absorb heatfrom and thereby cool the cylinder wall of an internal combustion engineP.

The engine P, which forms the prime mover element of the heating'system,directly drives a dynamoelectric machine Q. In normal operation,themachine Q acts as a generatorand has its terminals connected toservice conductors l and 2 by a switch S. The latter, however, may beadjusted to connect the terminals of the generator Q to the terminals ofa small storage battery R to energize the machine Q for operation as astarting motor for the engine 1?. The engine P is arranged to drive thepump M employed to circulate the heating medium The current generated bythe dynamoelectric machine Q energizes the motors IA, G and KA, when theswitch SA connects the service conductors l and 2 to the branch-serviceconductors 3 and 4, The conductors l and 2 when energized supplyenergizing current to fan motors TA operating fans T employed to moveair over the heat dissipating surfaces of the radiators O. The speed ofeach fan motor TA may be regulated by adjustment of a correspondingregulating rheostat T. The switch SA may be opened to interrupt theoperation of the heater during period in which the fan motors TA maycontinue in operation.

The liquid fuel, which may be gasoline, for example, is supplied underpressure from a suitable tank or other source, through one branch U froma supply pipe U, to the inlet of the heater pump 1, and through a secondbranch U from the supply pipe to the carburetor V of the internalcombustion engine P. The engine P is provided with a magneto W whichsupplies energizing current through a conductor 5 to the ignition meansP of the engine P, and supplies current through a conductor 6 toignition contacts 1 extending into the heating space B and employed tomaintain combustion in said space as long as a combustible mixture isbeing passed into the space through the orifices C. a

To avoid fire risk or other trouble due to the accumulation ofdeatomized' or condensed liquid fuel, such as gasoline, for example, inthe heater A when starting the apparatus into operation when cold, weprovide porous bodies of ceramic material in various portions of theapparatus to absorb and hold the deatomized or condensed gasolin untilthe apparatus warms up sufficiently to volatilize such gasoline. Thus,porous discs J of ceramic material are placed beneath the burner wall C,and a tubular porous body JA of ceramic material is arranged coaxiallywith the blower F and beneath the latter. The tubular body JA of porousceramic in 'the combustion air supply conduit E is beneath the region atwhich the fuel line H terminates at the vicinity of the fan F. In thisway, any liquid fuel discharged from the orifice H and passingdownwardly within the conduit E, as when the heater A is shut down, forexample, is collected within the conduit E to retard backward flow ofsuch fuel beyond a predetermined point in the air supply conduit. Whenoperation of the heater is subsequently started, following a shut downperiod, air passing through the conduit E picks u fuel collected by theporous body JA.

As will be apparent, wide variations in atmospheric pressure due tosubstantial changes in airplane altitude, do not prevent the desiredoperati'on of the heating system, since the use of the power actuatedpump 1, blower F, exhaust fan K and regulator K responsive toatmospheric pressure make it possible to move an adequate weight ofgasoline and combustion air into the combustion chamber B at all timeswhen the heater is in operation. While in accordance with the provisionsof thestatutes, we have illustrated and described the best form ofourinvention now known to us, it will be apparent to those skilled in theart that changes may be made in the form of the apparatus disclosedwithout departing from the spirit and scope ot-our invention, as setforth in the following claims.

Having now described our invention what-we claim as new and desire tosecure by Letters Patout is:

1. A- heater including structure providing a combustion space and aninlet space and a dividing wall therebetween having a numberof openingstherein, means including a blower having a rotatable fan therein and aliquid fuel line terminating in the vicinity of the fan for discharginga combustible mixture of atomized fuel and air into the inlet spacewhich is subdivided into a plurality of streams at the openings forcombustion in the combustion space, and a body of porous material in theinlet space in the path of fiow of the combustible mixture and anotherbody of porous material about a portion of the fuel line in the vicinityof the fan, said bodies beingprovided to absorb liquid fuel when theheater is relatively cool, as at starting, for exmeans including aliquid fuel line having a discharge orifice terminating in the passagefor dis charging fuel into the air stream to produce the combustiblemixture of air and fuel, said conduit means including a portionextending vertically downward from the region of the fuel dischargeorifice, and a body of porous material in said conduit means forabsorbing any liquid fuel which may fiow downwardly through thevertically extending portion thereof and from which fuel is picked up byair supplied to the heating space through the passage by said blower.

3. A heater including structure (providing a heating space adapted to beheated by combustion of a mixture of air and fuel, means providing apassage for supplying air to the space including conduit means and ablower therein, means including a liquid fuel'line having a dischargeorifice terminating in said passage for discharging fuel into the airstream to produce a combustible mixture of air and fuel,.said conduitmeans including a portion extending vertically downward from the regionof the discharge orifice of the fuel line, and means embodied in saidconduit means for collecting any liquid fuel which may fiow downwardlythrough the vertically extending portion thereof to retard backward flowof such a fuel beyond a. predetermined point in the air supply passage.

4. A heater including structure providing a heating'space adapted to beheated by combustion of a mixture of air and fuel, an air supplyconduit, means for supplying air to the space through said conduitcomprising a blower havin a rotatable fan therein, said conduitincluding a portion beneath said blower having a vertically extendingpart connected at its upper end to the inlet of the blower, meansincluding a liquid fuel line having a discharge orifice at the vicinityof the fan for discharging fuel into the air stream to producethe-combustible mixture of air and fuel, and a body of porous materialin the air supply conduit beneath the discharge orifice of the fuel lineto absorb any liquid fuel which may pass downwardly through thevertically extending part and from which fuel is picked up by airsupplied to the space through said conduit by said blower.

5. A heater including structure providing a heating space adapted to beheated by combustion of a mixture of air and fuel, an air supplyconduit, means for supplying air to the space through said conduitcomprising a blower having a rotatable fan therein, said air supplyconduit including a portion beneath said blower and having a verticallyextending part connected at its upper end to the inlet of the blower,means ineluding a. liquid fuel line having a discharge orifice at thevicinity of the fan for discharging fuel into the air stream to producethe combustible mixture of air and fuel, and means embodied in the airsupply conduit beneath the discharge orifice of the fuel line forcollecting any liquid fuel which may pass downwardly through thevertically extending part to retard backward flow of such fuel beyond apredetermined point in the I air supply conduit.

FREDERIC o. HESS. RICHARD E. B. WAKEFIELD.

